Noise suppressor

ABSTRACT

A noise suppressor for use in blowing natural gas storage field wells and capable of handling multiphase fluid flow is formed of a vertically-aligned elongated cylindrical housing with an inlet at its bottom end and an outlet at its top end. The housing is coated along its inside wall with a sound insulating material and has a deflecting baffle therein opposite and spaced from the inlet to prevent water, ice and/or hydrates from moving into the upper part of the housing. Above and spaced from the deflecting baffle is an annular baffle extending radially inwardly from the inside wall of the housing to block acoustic waves therein. Above and spaced from the annular baffle is a second deflecting baffle which also blocks acoustic waves. Again, above and spaced from this second deflecting baffle is a plurality of inclined vanes extending radially inwardly from the inside wall of the housing to assist in acoustic wave blockage. Also to block acoustic waves there is a turbulence-dampening grid formed of truck radiator core material above and in close proximity to the vanes. Finally, longitudinally-aligned hollow tubes formed of a sound insulating material may be attached to the housing above the turbulencedampening grid.

Grose Dec. 3, 1974 NOISE SUPPRESSOR 75] lnventorz Ronald D. Qmse, Omaha,ljebr. V [57] ABSTRACT 73] Assignee: Northern Natural Gas Company,Omaha,Nebr.

[22] Filed: Apr. 16, 1974 [21] Appl. No.: 461,304

[52] U.S. Cl 181/50, 55/276, 55/337, 55/462, 181/53, 181/58 [51] Int.Cl. ..F0lm1/10 [58] Field of Search 181/37, 50, 53,56, 57, 181/58, 66,67; 55/276, 321, 326, 337,416, 462, 464

[56] References Cited UNITED STATES PATENTS 1,606,032 11/1926Kolstrand..- 181/53 ux 3,454,129 7/1969 Everett 181/56 3,593,499 7/1971Kile 181/50 X 3,614,859 10/1971 Clark 181/53 X 3,757,892 9/1973Raudman... 181/50 X 3,776,365 12/1973 Richards .1 181/50 PrimaryExaminer-Richard B. Wilkinson Assistant Examiner-John F. GonzalesAttorney, Agent, or Firm-Donald F. Haas A noise suppressor for use inblowing natural gas storage field wells and capable of handlingmultiphase fluid flow is formed of a vertically-aligned elongatedcylindrical housing with an inlet at its bottom end and an outlet at itstop end. The housing is coated along its inside wall with a soundinsulating material and has a deflecting baffle therein opposite andspaced from the inlet to prevent water, ice and/or hydrates from movinginto the'upper part of the housing..Above and spaced from the deflectingbaffle is an annular baffle extending radially inwardly from the insidewall of the housing to block acoustic waves therein. Above andspacedfrom the annular baffle is a second deflecting baffle which alsoblocks acoustic waves. Again, above and spaced from this seconddeflecting baffle is a plurality of inclined vanes extending radiallyinwardly from the inside wall of the housing to assist in acoustic waveblockage. Also to block acoustic waves there is a turbulence-dampeninggrid formed of truck radiator core material above and in close proximityto the vanes. Finally, longitudinally-aligned hollow tubes formed of asound insulating material may be attached to the housing above theturbulence-dampening grid.

9 Claims, 4 Drawing Figures PATENTEp 3W 3.851.726

SHEET 10F 3 FIG. I

PATENTEL BEE 3 4 SHEET 2- OF 3 FIG. 2

1 NOISE SUPPRESSOR BACKGROUND OF THE INVENTION This invention generallyrelates to apparatus for attenuating noise and, more particularly,concerns a device for attenuating noises normally emanating from highvelocity fluid flow through an exhaust or escape passage. The presentinvention is primarily designed to decrease the noise to a decibel rangebelow the hazard level in accordance with the environmental conditionsof the particular application.

Investigation into the suppression of noise which is hazardous to healthor detrimental to a normal existence for both man and animals began inearnest in recent years with both private industry and governmentalagencies contributing to the research. While many noise suppressionproblems have been solved through the application of ordinaryengineering technology, some have defied the efforts of manyresearchers. Among these unsolved problems is that of the noise producedby rapid movement of fluid jets through the atmosphere. Such jet-inducednoise remains a largely unsolved problem despite the expenditures ofvast amounts of government and private funds.

The natural gas industry, for example, finds itself confronted with abasically unsolved problem in those situations where large volumes ofhigh-pressure gas must be released into the atmosphere. Such situationsarise in proving wells, testing and repairing pipelines, blowing storagefield wells, compressor stations startup and shutdown procedures, and invarious emergency operations. The present invention is particularlyapplicable to the solution of the blowdown noise problem which ariseswhen storage field wells are blown, although it is equally applicable toair and steam flow. The blowdown noise problem has been intensified bythe recent encroachment of residential areas upon gas storage fields.Whereas, in the past, the primary concern was with the physiologicaldamage caused to people working at the storage field, the residentialencroachment has made annoyance the principal factor in this area.Therefore, there is a real need for a noise attenuator which cansignificantly lower the level of blowdown noise.

The suppression of blowdown noise at the natural gas underground storagewellhead presents a constraint which is not found in the usual blowdownsituation. Such wells are plagued with excess water and natural gashydrate formations, thus causing blockage problems which necessitateclearing the well via the blowdown technique. Any suppressor placed onthe wellhead must, therefore, be designed to accommodate the passage oflarge masses of the hydrate and water without excessive back pressure sothat the well can be cleared. Also, the presence of water vapor and lowtemperatures must not cause the suppressor to become blocked because ofice formations within the suppressor. Up to the present time, thesuppressor design most frequently proposed to handle the blowdown noiseproblem at storage field wells is the so-called straight throughsuppressor wherein the gas, water, and hydrate jet is allowed to expandinto a sound insulated chamber with a much greater flow volume than theflow volume of the wellhead pipe and then pass into the atmosphere. Thisdesign does not provide very good sound attenuation.

Other devices which have been used to attenuate the noise in blowdownsituations are disclosed in US. Pat. Nos. 2,998,860 and 3,454,129 to W.S. Everett and US. Pat. No. 3,702,644 to N. Y. Fowler, Jr., et al. Allof these devices postulate sound attenuation, but only one of them(Everett US. Pat. NO. 2,998,860) can potentially handle the multiphasesituation which occurs Caulfield, and 3,447,630 to G. L. Davidson alldisclose devices which postulate that kind of sound attenuation. Thefirst of those patents discloses a device utilizing inclined vanes toassist in the sound attenuation. The present invention is designed tobeapplicable to all sound attenuation problems due to turbulent flow andto the above-mentioned blowdown noise problems in particular, whereasthe devices of these three patents cannot be utilized in the blowdownnoise situation.

SUMMARY OF THE INVENTION The present invention concerns an apparatus forattenuating noises which result when fluid escapes through an exhaustpassage at high velocity. The apparatus of this invention will decreasethe sound which can be perceived at some distance from the apparatus.The apparatus of this invention is basically formed of an elongatedcylindrical housing which is lined along its inside wall and asound-insulating material and which has an outlet at one end and aninlet at the other end. It should be noted at this point that while thefollowing description refers to the present invention in terms ofcylindrical, annular, and circular, the apparatus of this invention isby no means limited to such shapes even though they are preferred. Theinlet of the housing has a diameter substantially smaller than theinside diameter of the housing (as the gas pressure increases, the inletdiameter should be smaller in comparison to the housing inside diameter)and is adaptable to be connected to a fluid exhaust passage. There is anupstream impact baffle located within and attached to the cylindricalhousing to deflect the flow of fluid entering the inlet. The upstreambaffle is positioned between and spaced from the inlet and the'outlet,and has a diameter smaller than the inside diameter of the cylindricalhousing but greater than the diameter of the inlet. The primary purposesof the upstream baffle are (I) to separate water from the gas, (2) todisintegrate solids, such as ice, in the fluid flow, and (3) to reducethe velocity of the fluid flow, and thereby its kinetic energy, beforethe gas leaves the suppressor. Further, there is a plurality of inclinedvanes attached to and extending radially inwardly from the inside wallof the cylindrical housing. The inclination of these vanes is such thatfluid flow openings are defined between them. The vanes are positionedbetween and spaced from the upstream baffle and the outlet. Finally, afluid permeable turbulencedampening grid is attached to and positionedacross the entire inside cross-section of the cylindrical housingbetween the vanes and the outlet. The grid is located in outlet. Theprimary purpose of the vanes and grid is to block the acoustic wavescreated by the reduction in kinetic energy at the upstream baffle andthus decrease the amount of acoustic energy entering the atmosphere.

The apparatus described above may also have an annular baffle attachedto the housing and positioned therein between and spaced from theupstream baffle and the vanes. This annular baffle extends radiallyinwardly from the inside wall of the cylindrical housing and defines afluid flow passage with a diameter smaller than the diameter of theupstream baffle. The primary purpose of the annular baffle is to helpblock the acoustic waves within the suppressor.

The above-described apparatus may also have a downstream baffle locatedwithin andattached to the cylindrical housing, and positioned betweenand spaced from the annular baffle and the vanes. Fluid flowing throughthe fluid flow passage defined by the annular baffle will be deflectedby this downstream baffle. The downstream baffle has a diameter smallerthan the inside diameter of the cylindrical housing, but greater thanthe diameter of the fluid flow passage defined by the annular baffle.Its primary purpose is also to help block acoustic waves. Additionaldownstream baffles may be added to assist blocking.

The above apparatus can have a number of hollow acoustic cylindricaltubes formed of a sound-insulating materialattached to the housingdownstream of the turbulence-dampening grid. These tubes should beplaced in longitudinal alignment with the housing and are utilized toprovide more exposed acoustically-lined surface areafor additional soundattenuation.

To help accommodate multiphase fluid flow, the apparatus of thisinvention can utilize a nongaseous material removal system. Such asystem may utilize a hollow cylindrical separation drum with theupstream baffle forming the downstream end of the drum. The drum is openat its upstream end and has an annularly-shaped inwardly-extendingdownstream-facing gutter thereat. Fluid from the inlet flows into thedrum through its open end, is deflected back upstream and flows out ofthe drum through the same open end, and while this is going on thegutter skims the nongaseous material from the fluid and collects it. Thegutter has a plurality of drains thereon which convey the nongaseousmaterial from the drum and facilitate its removal from the housing. Thedrains support they drum and can themselves be supported on and extendthrough an annular supporting baffle which is attached to the housingand located upstream of the drum. The inlet extends through this annularsupporting baffle without contacting it. This annular supporting baffledeflects the fluid downstream around the drum.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of theapparatus of the present invention showing it as it would be used tosuppress blowdown noise from a gas storage field wellhead.

FIG. 2 is a longitudinal cross-section taken along line 2-2 of FIG. 1.

FIG. 3 is a closeup cut-away view of the apparatus illustrated by FIG.1, showing the turbulence-dampening grid and the inclined vanes.

FIG. 4 is a plan view of the apparatus illustrated by FIG. 1 with mostof the end cap removed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The noise suppressor 10illustrated by the accompanying FIGS. 1 to 4 is the preferred embodimentof the present invention and is particularly applicable to theattenuation of blowdown noise. It should be recognized that there aremany other configurations which are also within the scope of theinvention. The noise suppressor 10, as illustrated in FIG 1, isvertically aligned because it has been found that when there is ice inthe fluid flow from the underground storage well, curved or Lshapedinlet pipes can rupture. The suppressor 10 is rotatably mounted aboveground level by arms 11 on a supporting column 12 so that the suppressor10 can be easily connected to or disconnected from the wellhead valve(not shown) and swung to the side out of the way. The column 12 isitself stabilized by legs 14 which are affixed to concrete blocks 16sunk into the ground, as is the column 12.

. The noise suppressor 10 itself is comprised of a substantially hollowcylindrical housing 18 having a fluid inlet pipe 20 at its bottom endand a top end cap 22 at its top end. The top end cap 22 has an insidediameter which is substantially larger than the outside diameter of thecylindrical housing 18 and is removably supported on the housing 18 bystruts 24 such that there is a substantial area between the top edge ofthe hous ing 18 and the cap 22 for fluid to flow out of the housing 18.The principal purpose of the cap 22 is to protect the suppressor 10 fromrain, snow, sleet, etc., but it also assists in blocking acoustic waves.Additionally, emergency pressure relief blowout doors 26 are located onthe outside of the housing 18.

Turning our attention to FIG. 2, it can be seen that the cylindricalhousing 18 is comprised of a lower section 28 and an upper section 30 tofacilitate maintenance. The sections 28 and 30 have outwardly extendingupwardly and downwardly facing, respectively, concentric flanges 32 and34 at their upper and lower edges, respectively. The flanges 32 and 34are bolted together at several locations 36 around the outside of thehousing 18 to provide a pressure-tight fluid impermeable seal betweenthe sections 28 and 30.

The fluid inlet pipe 20 has a saw-toothed upper end and extends upwardlywell into the hollow interior of the housing 18 but has no directcontact with the housing 18. The inlet pipe 20 is supported therein onlyby reinforced rubber gasket 38 which is clamped to the inlet pipe 20 andthe inside wall of the housing 18. The purpose of gasket 38 is toprevent the transfer of vibration from the inlet pipe 20 to the rest ofthe suppressor l0 and thus achieve a significant reduction in the noiselevel. The gasket 38 may be made of any suitable material which willsupport the inlet pipe 20 and not transfer its vibrations (conventionalwellhead casing seals are used in the preferred embodiment).

Positioned directly above the upper end of the inlet pipe 20 andconcentric with the horizontal crosssection of the cylindrical housing18 is the convex (with respect to the fluid flow direction) upstreambaffle 40. The upstream baffle 40, which is substantially greater indiameter than inlet pipe 20, deflects the fluid flow from the inlet pipe20 downwardly to prevent any water, ice, or hydrates therein from movinginto the upper section 30 of the housing 18 and to disintegrate thesolid material in the fluid flow. The baffle 40 also reduces thevelocity of the fluid flow and thereby its kinetic energy. The baffle 40forms the top end of cylindrical'separation drum 42 which is open at itsbottom end and also has a V-shaped gutter 44 at its bottom end. Thegutter 44 operates to skim the water, ice, and hydrates out of the gasflow.

It is theorized that as it is deflected downwardly by the baffle 40, thefluid swirls inside the drum 42 at high velocity in an annular doughnutpattern. The water, ice, and hydrates are disengaged from the gas bycentrifugal forces and direct impact with the inside wall of the drum42, and flow down the inside wall into the gutter 44. Next, the waterflows into small drains 46 at the bottom of the gutter 44, down to thebottom of section 28, and out of the housing 18 through drain pipe 48which is within the lower arm 1 1 (see FIG. 1). From the arm 11, thewater flows into the supporting column 12 and out of the water outlet50. The outlet 50 has an automatic dump valve (not shown) to preventventing of gas therethrough if there is no water in the column 12.

The gas flows out of the drum 42 through the opening in the gutter 44 atthe bottom of the drum 42 and is deflected upwardly around the outsideof the drum 42 by concave (with respect to the gas flow direction) lowerbaffle 52. Lower baffle 52 protects the draining water from the chaoticmotions of the gas as it makes a 180 flow direction reversal. Note thatthe inlet pipe extends upwardly through the baffle 52 without contactingit. The drum 42 is supported on the lower baffle 52 by the small drains46. The lower baffle 52, in turn, is supported on the bottom wall of thehousing 18 by supporting cylinder 54 which is slotted (not shown) toallow water to flow out drain pipe 48. The cylinder 54 has ahorizontally outwardly extending flange 56 which is bolted at 58 to thehousing 18.

Located above the upstream baffle 40 is the annular baffle 60 which iswelded to crossed I-beams 61 having end flanges 62 which themselves arebolted at 64 to the inside wall of the housing 18 to support the annularbaffle 60. Upstream baffle 40 and drum 42 are also welded to l-beams 61for primary structural support. To provide the maximum soundattenuation, the baffle 60 must be spaced sufficiently from the bottomend of the housing 18 to provide an expansion chamber therebetween witha flow volume very much greater than that of the inlet pipe 20. The gasflows up around the drum 42 through the opening in the annular baffle60, which should be somewhat smaller in diameter than the upstreambaffle 40. Located directly above the opening in the annular baffle 60to again deflect the flow of the gas, is downstream baffle 66. Thedownstream baffle 66 is greater in diameter than the opening in theannular baffle 60 and is supported by the l-beams 61, to which it iswelded. The primary purpose of the downstream baffle 66, as well as theannular baffle 60, is to block acoustic waves produced within thesuppressor 10, thereby lowering the noise level perceived at a distancefrom the suppressor 10. Additionally, these baffles further'reduce thevelocity of the gas flow and thereby its kinetic energy.

The emergency pressure relief doors 26 are formed in the side wall ofthe upper section of the housing 18 just above the baffle 66. The doors26 are symmetrically aligned in pairs to prevent asymmetrical forcesfrom knocking the suppressor 10 over. The doors 26 are held in place bypairs of attached rods 68 which are designed to give way and release thedoors 26 if the pressure inside the suppressor 10 reaches a dangerouslevel. Triangular-shaped stops 63, which are welded to the l-beams 61and which have apertures through which the rods 68 can movereciprocally, prevent the doors 26 from becoming projectiles. The rods68 have crumpable sleeves 65 and springs 65A thereon which contact thestops 63 as the rods 68 move outwardly to absorb the kinetic energy ofthe doors 26 and halt their outward movement. Structural restraint 67prevents the stops 63 from bending under the impact load due to theoutwardly moving doors 26.

A plurality of'vanes 70 are located just above the blowout doors 26. Thevanes 70 extend radially inwardly from the inside wall of the housing 18and are inclined to provide fluid or gas flow openings between them. Inorder to obtain acceptable results, the inclination of the vanes 70should be greater than 10 from the horizontal (here the inclination is20). FIG. 3 illus trates the vanes 70 and the fluid permeableturbulencedampening grid 72, which is located just above the vanes 70,in more detail. The turbulence-dampening grid 72 extends across theentire inside cross-section of the housing 18 and is preferably formedof truck radiator core material. It is supported on the vanes 70. Anymaterial which has a high aspect ratio, i.e., long fluid flow channelscompared to the size of the openings, and which does not itself createturbulence can be utilized in the turbulence-dampening grid 72. Theelements which form the fluid flow channels are prefer-a bly ,very thinin comparison to the size of the openings and no sound insulatingmaterial is used within the grid 72. The grid 72 is restrained fromupward movement (as might occur if the grid 72 becomes blocked by ice)by restraining member 73 which is comprised of a number of hollowcylindrical pieces welded together. The restraining member 73 is weldedto flanged retaining ring 75 which, in turn, is attached to the housing18. The chief beneficial action of the inclined vanes 70 and theturbulence-dampening grid 72 is blockage of the acoustic waves producedwithin the suppressor 10, thereby decreasing the sound level perceivedat a distance from the suppressor 10.

In addition to the above noise attenuation elements, the entire insidewall of the cylindrical housing 18 should be coated with a soundinsulating material 78 such as, for example, waterproofed open-cellpolyurethane foam. The material 78 is held in place by end retainingring 80. It has been found that better noise attenuation is obtained asthe ratio of exposed acoustically-linedsurface area to cross-sectionalarea within the housing is increased. lf the fluid flow rate is at avery high level, it becomes economically advantageous to increase theexposed acoustically-lined surface area without unduly increasing theheight of the suppressor 10. As illustrated in FIG. 4, this isaccomplished by placing hollow acoustic tubes 74 in the upper section 30of the housing 18 above the hollow cylinders of the restraining member73. The tubes 74 are removably attached to the member 73 and arepreferably made of waterproofed open-cell polyurethane foam held inplace by formed wire mesh.

For example, at a gas flow rate of pounds per second, a decrease of30-35 decibels at a distance of 50 feet from the suppressor 10 can beobtained without using the tubes 74. At a gas flow rate of 140 poundsper second, the same attenuation can be obtained by using the tubes 74without increasing the length of the suppressor 10.

I claim:

1. An apparatus for attenuating noises which result when fluid escapesthrough an exhaust passage at high velocity, said apparatus comprising:

a. an elongated cylindrical housing lined along its inside wall with asound-insulating material and having an outlet at'one end and an inletat the other end, said inlet having a diameter substantially smallerthan the inside diameter of said cylindrical housing and adaptable to beconnected to a fluid exhaust passage;

b. an upstream impact baffle located within and attached to saidcylindrical housing, and positioned between and spaced from said inletand said outlet to deflect the flow of fluid entering said inlet, saidbaffle having a diameter smaller than the inside diameter of saidcylindrical housing and greater than the diameter of said inlet;

a plurality of inclined vanes attached to and extending radiallyinwardly from said inside wall of said cylindrical housing such thatfluid flow openings are defined between said vanes, said vanespositioned between and spaced from said upstream baffle and said outlet;and

d. a fluid-permeable turbulence-dampening grid attached to andpositioned across the entire inside cross-section of said cylindricalhousing between said vanes and said outlet, said turbulencedampeninggrid being located in close proximity to said vanes and spaced from saidoutlet.

2. An apparatus as defined in claim 1 and further characterized in thatan annular baffle is attached to said housing and positioned thereinbetween and spaced from said upstream baffle and said vanes, saidannular baffle extending radially inwardly from said inside wall of saidcylindrical housing and defining a fluid flow passage with a diametersmaller than the diameter of said upstream baffle.

3. An apparatus as defined in-claim 2 and further characterized in thatadownstream baffle is located within and attached to said cylindricalhousing, and is positioned between and spaced from said annular baffleand said vanes such that fluid flowing through said fluid flow passagedefined by said annular baffle is deflected by said downstream baffle,said downstream baffle having a diameter smaller than the diameter ofsaid cylindrical housing and greater than the diameter of said fluidflow passage defined by said annular baffle.

4. An apparatus as defined in claim 3 and further characterized in thatat least one hollow acoustic cylindrical tube formed of saidsound-insulating material is removably attached to said housing inlongitudinal alignment therewith to provide additional exposedacoustically-lined surface area, said tube positioned downstream of saidgrid.

5. An apparatus as defined in claim 4 and further characterized in thata nongaseous material removal system is included within said housing,said system comprising: 7

a. a hollow cylindrical separation drum of which said upstream baffleforms the downstream end and which is open at its upstream end to allowfluid from said inlet to flow into and out of said drum;

b. an annularly-shaped inwardly-extending downstream-facing gutter atthe upstream end of said drum for skimming said nongaseous material fromthe fluid flowing therein and for collecting said nongaseous material;and

c. a plurality of drains attached to said housing and extending fromsaid gutter to support said drum within said housing and to convey saidnongaseous material from said drum to facilitate removal'of saidnongaseous material from said housing.

6.. An apparatus as defined in claim 5 and further characterized in thatsaid drains are attached to and extend through an annular supportingbaffle which is attached to said housing and is positioned thereinupstream of said drum, said. supporting baffle defining an openingthrough which said inlet extends without actually contacting saidsupporting baffle.

7. An apparatus as defined in claim 5 and characterized further in thatsaid inlet is supportedin said housing by a reinforced rubber gasketwhich prevents the vibrations of said inlet from being transferred tosaid housing, said gasket being the only point of contact between saidinlet and said housing.

8. An apparatus as defined in claim 7 and characterized further in thatat least one pair of symmetrically aligned blowout doors are formed inthe side wall of said housing to provide emergency pressure relief, saidpair of doors are held in place by pairs of attached rods which aredesigned to release said doors at a desired pressure, at least two stopmeans are attached to said housing, said rods positioned for reciprocalmovement through apertures in said stop means, and said rods, havesprings and crumpable sleeves mounted thereon to contact said stopmeans, absorb the kinetic energy of said doors, and halt the outwardmovement of said doors.

9. An apparatus as defined in claim 8 and characterized further in thatsaid housing has an end cap mounted thereon at the outlet thereof, toallow fluid flow between said end cap and said housing, said end caphaving an inside diameter substantially larger than the outside diameterof said housing.

1. An apparatus for attenuating noises which result when fluid escapesthrough an exhaust passage at high velocity, said apparatus comprising:a. an elongated cylindrical housing lined along its inside wall with asound-insulating material and having an outlet at one end and an inletat the other end, said inlet having a diameter substantially smallerthan the inside diameter of said cylindrical housing and adaptable to beconnected to a fluid exhaust passage; b. an upstream impact bafflelocated within and attached to said cylindrical housing, and positionedbetween and spaced from said inlet and said outlet to deflect the flowof fluid entering said inlet, said baffle having a diameter smaller thanthe inside diameter of said cylindrical housing and greater than thediameter of said inlet; c. a plurality of inclined vanes attached to andextending radially inwardly from said inside wall of said cylindricalhousing such that fluid flow openings are defined between said vanes,said vanes positioned between and spaced from said upstream baffle andsaid outlet; and d. a fluid-permeable turbulence-dampening grid attachedto and positioned across the entire inside cross-section of saidcylindrical housing between saiD vanes and said outlet, saidturbulence-dampening grid being located in close proximity to said vanesand spaced from said outlet.
 2. An apparatus as defined in claim 1 andfurther characterized in that an annular baffle is attached to saidhousing and positioned therein between and spaced from said upstreambaffle and said vanes, said annular baffle extending radially inwardlyfrom said inside wall of said cylindrical housing and defining a fluidflow passage with a diameter smaller than the diameter of said upstreambaffle.
 3. An apparatus as defined in claim 2 and further characterizedin that a downstream baffle is located within and attached to saidcylindrical housing, and is positioned between and spaced from saidannular baffle and said vanes such that fluid flowing through said fluidflow passage defined by said annular baffle is deflected by saiddownstream baffle, said downstream baffle having a diameter smaller thanthe diameter of said cylindrical housing and greater than the diameterof said fluid flow passage defined by said annular baffle.
 4. Anapparatus as defined in claim 3 and further characterized in that atleast one hollow acoustic cylindrical tube formed of saidsound-insulating material is removably attached to said housing inlongitudinal alignment therewith to provide additional exposedacoustically-lined surface area, said tube positioned downstream of saidgrid.
 5. An apparatus as defined in claim 4 and further characterized inthat a nongaseous material removal system is included within saidhousing, said system comprising: a. a hollow cylindrical separation drumof which said upstream baffle forms the downstream end and which is openat its upstream end to allow fluid from said inlet to flow into and outof said drum; b. an annularly-shaped inwardly-extendingdownstream-facing gutter at the upstream end of said drum for skimmingsaid nongaseous material from the fluid flowing therein and forcollecting said nongaseous material; and c. a plurality of drainsattached to said housing and extending from said gutter to support saiddrum within said housing and to convey said nongaseous material fromsaid drum to facilitate removal of said nongaseous material from saidhousing.
 6. An apparatus as defined in claim 5 and further characterizedin that said drains are attached to and extend through an annularsupporting baffle which is attached to said housing and is positionedtherein upstream of said drum, said supporting baffle defining anopening through which said inlet extends without actually contactingsaid supporting baffle.
 7. An apparatus as defined in claim 5 andcharacterized further in that said inlet is supported in said housing bya reinforced rubber gasket which prevents the vibrations of said inletfrom being transferred to said housing, said gasket being the only pointof contact between said inlet and said housing.
 8. An apparatus asdefined in claim 7 and characterized further in that at least one pairof symmetrically aligned blowout doors are formed in the side wall ofsaid housing to provide emergency pressure relief, said pair of doorsare held in place by pairs of attached rods which are designed torelease said doors at a desired pressure, at least two stop means areattached to said housing, said rods positioned for reciprocal movementthrough apertures in said stop means, and said rods have springs andcrumpable sleeves mounted thereon to contact said stop means, absorb thekinetic energy of said doors, and halt the outward movement of saiddoors.
 9. An apparatus as defined in claim 8 and characterized furtherin that said housing has an end cap mounted thereon at the outletthereof, to allow fluid flow between said end cap and said housing, saidend cap having an inside diameter substantially larger than the outsidediameter of said housing.